Structural components in an aircraft can be made of a supported skin that forms the shape of the component. In some cases, the skin is made of multiple skin members that form the desired shape. For example, the skin members can be contoured sheets or plates of metal or composite materials that are attached at the edges. For aircraft structural components, it is desirable to minimize weight while maintaining stability and structural integrity. Reducing the weight of structural components can reduce fuel consumption and reduce the size of engines used to maintain flight operation. In some cases, to provide stability and rigidity, the components are filled with a foam, such as an expandable polyurethane foam or machined foam inserts. A foam can provide structural support at a lower weight than other techniques, such as metal or plastic supports.